Hygroscopic monolith

ABSTRACT

A monolithic hygroscopic material shaped to facilitate a circulation flow of ambient air. The hygroscopic material may be used to remove various compounds from an ambient gas and may be reactivated to restore its drying capacity. The tendency of the material to seek equilibrium may be utilized to achieve dehumidification or humidification.

This application is a continuation of Ser. No. 09/157,208, filed Sep.18, 1998, now U.S. Pat. No. 6,280,504.

BACKGROUND OF THE INVENTION

The present invention relates to dehumidifiers. More particularly, thepresent invention relates to a hygroscopic material having a shape andsurface area orientation which facilitates circulation and drying of aworking gas.

Dehumidifiers are used to dry working gases, such as water vapor in air.Typical desiccant dehumidifying machines blow the air or working gasacross a desiccant material to remove the vapor from the working gas.These types of machines require a power source and typically utilizemoving parts to dry the working space. In addition, the desiccant istypically contained or packaged within the machine and the vapor richair is mechanically passed across the desiccant. In addition torequiring active intervention to turn the machine ON and OFF, suchdevices are limited by their power needs, the breakdown of the movingmechanical components, and a somewhat inefficient use of the desiccantmaterial.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a shaped monolithichygroscopic material which moves air through a “chimney effect” or airdensity differences in and around the material. The present inventionthus provides a passive dehumidifier which allows direct contact withthe gas being dried without the need for an outside power source, movingparts, or packaging of a desiccant material. Alternatively, the tendencyof the material to seek equilibrium with the working gas may also beutilized to achieve humidification.

The present invention comprises a hygroscopic material having at leastone passageway or channel therethrough. The material is shaped toprovide a surface area to facilitate gas flow, and drying of an ambientgas by creating a chimney effect which facilitates mixing of the gas.This causes the heavier water vapor or other compound containing gas tocontact adsorbent material adjacent to the passageway or channel, adsorbat least some of the compound, and cause the lighter gas to exit thepassageway or channel. The dehumidifier may have various shapes andsizes and can be reactivated to restore its drying capacity. Whenutilized as a humidifier, the material desorbs or adds the constituent(such as water vapor) to the gas and a downdraft rather than a chimneyeffect is achieved.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one embodiment of the present inventionillustrating flow of air or other gas therethrough.

FIG. 2 is a phantom view of FIG. 1.

FIG. 3 is a cross-sectional view taken along section lines 3—3 of FIG.2.

FIG. 4 is a perspective view of an alternate embodiment of the presentinvention illustrating air or other gas flow therethrough.

FIG. 5 is a top view of FIG. 4.

FIG. 6 is a cross sectional view taken along section lines 6—6 of FIG.4.

FIG. 7 is a perspective view of a further alternate embodiment of thepresent invention illustrating air or other gas flow therethrough.

FIG. 8 is a top view of FIG. 7.

FIG. 9 is a cross sectional view taken along section lines 9—9 of FIG.7.

FIG. 10 is a side view of an embodiment of the present inventionutilized as a humidifier and illustrating alternate flow of air or othergas therethrough.

FIG. 11 is a graph illustrating the data reflected in Table 1.

FIG. 12 is a graph illustrating the data reflected in Table 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, FIG. 2 and FIG. 3, an embodiment of the presentinvention is identified by the number 14. For purposes of the presentdescription, it will be described in connection with its usage as adehumidifier 14. The dehumidifier 14 comprises a shaped, monolithichygroscopic material 16. The material 16 has a plurality of externalsurface areas which include a plurality of generally square externalsurfaces 18 and a plurality of generally triangular external surfaces20. The material 16 has a generally polyhedron or faceted shape.

As further illustrated in FIG. 2, the material 16 has a plurality ofchannels or passageways 22 therethrough. Each passageway 22 has an inletport and an outlet port, identified generally by the number 24.Depending upon the orientation of the material 16, any port 24 mayfunction as an inlet port or outlet port. As illustrated in FIG. 3, eachpassageway 22 has an internal surface 26. Each passageway 22 isgenerally cylindrical, passes from one side of material 16 to anopposite side, and has a plurality of other passages 22 in fluidcommunication with and generally perpendicular thereto.

Referring again to FIG. 1, the usage and operation of the dehumidifier14 will be described in greater detail. The dehumidifier 14 may beplaced in any environment having water vapor or other compound orconstituent (for which dehumidifier 14 has an affinity) within a workinggas, such as air. When the heavier, denser compound/vapor laden gas(dotted arrows) enters an inlet port 24 it is dried by the surface area26 of the adsorbent material 16 within the corresponding passageway 22.The lighter, drier air (clear arrows) thereafter exits through a port24. As the dry air rises, a circulation or “chimney” effect is createdwithin the working environment, as illustrated by the arrows in FIG. 1.That is, the lighter, drier air rises from the dehumidifier 14 and theheavier, vapor laden air is circulated to enter the dehumidifier 14(passages 22) so that the water vapor or other constituent of the gas isadsorbed (or absorbed) by material 16. Surfaces 18 and 20 may alsoprovide some adsorption (or absorption) of the gaseous constituent.

Testing of the embodiment of FIG. 1 yielded the results reflected inTable 1, as graphically depicted in FIG. 11. In the test, a dehumidifier14 having a mass of approximately 10 grams (natural zeolite) wasactivated (dried) in a microwave oven and placed in a sealed, one literglass beaker with a probe for measuring temperature (degreesFahrenheit), relative humidity (% Rh), dewpoint (degrees Fahrenheit),and absolute humidity (grains per pound). Readings of the probe weretaken every thirty seconds. As evidenced by the data collected, thedehumidifier 14 rapidly and efficiently dried the air in the beaker.

TABLE 1 Dehumidification Data, 1 liter air volume, 30 sec intervalRelative Dewpoint Absolute Humidity Temp Temp. Humidity Time Rh T Td x tA B C D E 1 57.1 75.5 59.4 75.4 0 2 30.2 75.5 40.6 36 0.5 3 23.8 75.535.4 29.6 1 4 15.7 75.6 25.7 19.6 1.5 5 11.8 75.6 18.8 15.1 2 6 8.9 75.712.4 11.6 2.5 7 7.1 75.7 7.5 9.15 3 8 5.8 75.7 3.1 7.4 3.5 9 4.8 75.8−0.9 6.16 4 10 4.1 75.8 −4.4 5.16 4.5 11 3.5 75.8 −7.3 4.55 5 12 3.175.8 −9.9 4 5.5 13 2.7 75.8 −12.4 3.56 6 14 2.4 75.9 −14.6 3.14 6.5 152.2 75.9 −16.3 3.09 7 16 2 75.9 −18.1 2.68 7.5 17 1.8 75.9 −19.9 2.4 818 1.7 75.9 −21 2.26 8.5 19 1.6 75.9 −22.4 2.1 9 20 1.5 75.9 −23.7 1.989.5 21 1.4 76 −24.6 1.88 10 22 1.3 76 −25.7 1.77 10.5 23 1.3 76 −26.61.67 11 24 1.2 76 −27.6 1.59 11.5 25 1.1 76 −28.6 1.5 12 26 1.1 76 −29.41.45 12.5 27 1 76.1 −30.3 1.39 13 28 1 76.1 −31 1.31 13.5 29 1 76.1−31.6 1.31 14 30 0.9 76.1 −32.5 1.23 14.5 31 0.9 76.1 −33.2 1.16 15 320.9 76.1 −33.8 1.14 15.5 33 0.8 76.1 −34.3 1.08 16 34 0.8 76.1 −35 1.0616.5 35 0.8 76.1 −35.4 1.04 17 36 0.8 76.1 −36 0.99 17.5 37 0.7 76.1−36.5 0.98 18 38 0.7 76.1 −37 0.94 18.5 39 0.7 76.1 −37.6 0.91 19 40 0.776.1 −38 0.88 19.5 41 0.6 76.1 −38.6 0.86 20 42 0.6 76.1 −39 0.83 20.543 0.6 76.1 −39.7 0.81 21 44 0.6 76.1 −40 0.77 21.5 45 0.6 76.1 −40.50.76 22 46 0.6 76.1 −41 0.74 22.5 47 0.5 76.1 −41.4 0.72 23 48 0.5 76.1−41.8 0.71 23.5 49 0.5 76.1 −42 0.69 24 50 0.5 76.1 −42.4 0.67 24.5 510.5 76.1 −43 0.66 25 52 0.5 76.1 −43.3 0.65 25.5 53 0.5 76.1 −43.7 0.6326 54 0.5 76.1 −44.2 0.61 26.5 55 0.5 76.1 −44.6 0.6 27 56 0.4 76.1 −450.59 27.5 57 0.4 76.2 −45.3 0.58 28 58 0.4 76.2 −45.8 0.56 28.5 59 0.476.2 −46 0.55 29 60 0.4 76.2 −46.2 0.54 29.5 61 0.4 76.2 −46.8 0.53 3062 0.4 76.2 −47 0.51 30.5 63 0.4 76.2 −47.3 0.5 31 64 0.4 76.2 −47.7 0.531.5 65 0.4 76.2 −48 0.49 32 66 0.4 76.2 −48.4 0.48 32.5 67 0.3 76.2−48.7 0.47 33 68 0.3 76.2 −49 0.45 33.5 69 0.3 76.2 −49.4 0.45 34 70 0.376.2 −49.9 0.43 34.5 71 0.3 76.2 −50 0.42 35 72 0.3 76.2 −50.8 0.41 35.573 0.3 76.2 −51 0.4 36 74 0.3 76.2 −51.6 0.39 36.5 75 0.3 76.2 −51.80.39 37 76 77 0.2 76.2 −60.7 0.22 61.5 78 0.2 76.2 −61 0.21 89.5

Referring to FIG. 4, FIG. 5 and FIG. 6, an alternate embodiment of thepresent invention is identified by the number 30. For purposes of thepresent description, it will be described in connection with its usageas a dehumidifier 30. The dehumidifier 30 comprises a shaped, monolithichygroscopic material 32. The material 32 has a plurality of generallyrectangular columns 34 which define a plurality of external channels 36therein. Each channel 36 has internal surfaces 38. Channels 36 extendthe length L, width W, and depth D of dehumidifier 30 and the length Lis generally twice the width W and twice the depth D with the width Wand depth D being approximately equal. The material 32 has a generallycolumnar shape, a plurality of generally square external surfaces 40 anda plurality of generally rectangular external surfaces 42.

Referring again to FIG. 5 and FIG. 6, the material 32 further comprisesa cylindrical internal passageway 44 therethrough. Passageway 44 has aninlet port 45 on a first lengthwise end of dehumidifier 30 and an outletport 46 on a second, opposite lengthwise end of dehumidifier 30.Passageway 44 extends from channel 36 on one lengthwise end ofdehumidifier 30 to channel 36 on the opposite lengthwise end and has aninternal surface 48. As may be readily understood, ports 44 and 45 mayeach serve as an inlet port and an outlet port, depending upon theorientation of the dehumidifier 30.

Referring again to FIG. 4, the usage and operation of the dehumidifier30 will be described in greater detail. The dehumidifier 30 may beplaced in any environment having water vapor or other compound orconstituent (for which dehumidifier 30 has an affinity) within a workinggas, such as air. When the heavier, denser compound/vapor laden gas(dotted arrows) enters the channels 36 it is dried by the surface area38 of the adsorbent material 32 within the corresponding channel 36. Thelighter, drier air (clear arrows) thereafter exits the respectivechannel 36. Likewise, heavier, denser compound/vapor laden gas (dottedarrows) enters inlet port 45 and is dried by the surface area 48 of theadsorbent material 32 within passageway 44. The lighter, drier air(clear arrows) thereafter exits through exit port 46. As the dry airfrom channels 36 and passage 44 rises, a circulation or “chimney” effectis created within the working environment, as illustrated by the arrowsin FIG. 4. That is, the lighter, drier air rises from the dehumidifier30 and the heavier, vapor laden air is circulated to enter thedehumidifier 30 (channels 36 and passage 44) so that the water vapor orother constituent of the gas is adsorbed (or absorbed) by material 32.Surfaces 40 and 42 may also provide some adsorption (or absorption) ofthe gaseous constituent.

Testing of the embodiment of FIG. 4 yielded the results reflected inTable 2, as graphically depicted in FIG. 12. In the test, a dehumidifier30 having a mass of approximately 40 grams (natural zeolite) wasactivated (dried) in a microwave oven and placed in a sealed one literglass beaker with a probe for measuring temperature (degreesFahrenheit), relative humidity (% Rh), dewpoint (degrees Fahrenheit),and absolute humidity (grains per pound). Readings of the probe weretaken every thirty seconds. As evidenced by the data collected, thedehumidifier 30 rapidly and efficiently dried the air in the beaker.

TABLE 2 Dehumidification Data, 1 liter air volume, 30 sec intervalRelative Dewpoint Absolute Humidity Temp Temp. Humidity Time Rh T Td X tA B C D E 1 51.1 68.2 49.4 52.2 0 2 38.7 68.5 41.8 38.5 0.5 3 33.7 68.638.5 33.9 1 4 28.3 68.8 34.4 28.9 1.5 5 23.3 68.8 29.8 24 2 6 20.3 68.926.3 20.7 2.5 7 17.4 69 22.8 17.9 3 8 15.7 69.1 20.5 16.2 3.5 9 13.669.2 17.3 14.2 4 10 12.4 69.3 15.1 12.9 4.5 11 11.3 69.3 13.3 11.9 5 1210.5 69.4 11.5 11 5.5 13 9.7 69.5 9.8 10.2 6 14 8.9 69.6 8.3 9.51 6.5 158.4 69.7 6.6 8.82 7 16 7.9 69.7 5.5 8.4 7.5 17 7.4 69.8 4.3 7.91 8 18 769.9 3 7.48 8.5 19 6.6 69.9 1.9 7.09 9 20 6.3 70 1 6.76 9.5 21 6 70.1 06.48 10 22 5.8 70.2 −0.9 6.2 10.5 23 5.5 70.2 −1.9 5.93 11 24 5.2 70.3−2.8 5.67 11.5 25 5 70.4 −3.6 5.45 12 26 4.8 70.4 −4.4 5.26 12.5 27 4.770.5 −5.1 5.08 13 28 4.5 70.5 −5.8 4.89 13.5 29 4.3 70.5 −6.5 4.73 14 304.2 70.6 −7.2 4.57 14.5 31 4 70.6 −7.9 4.43 15 32 3.2 70.5 −13 3.43 2033 2.7 70 −16.1 2.93 25.5 34 2.5 70.1 −18.1 2.66 30.5 35 2.3 70.6 −19.42.49 40.5 36 1.3 70.3 −29.6 1.42 65.5

Referring to FIG. 7, FIG. 8 and FIG. 9, another embodiment of thepresent invention is identified by the number 50. For purposes of thepresent description, it will be described in connection with its usageas a dehumidifier 50. The dehumidifier 50 comprises a shaped, monolithichygroscopic material 52. The material 52 has a plurality of externalsurface areas which include a plurality of generally square externalsurfaces 54 and a plurality of generally rectangular surface areas 56.

As further illustrated in FIG. 7 and FIG. 8, the material 52 has aplurality of channels 58 therein. Each channel 58 has internal surfaces60. Channels 58 extend the length L, width W, and depth D ofdehumidifier 50 with the length L, width W and depth D beingapproximately equal so as to form a generally cubed shape.

Referring again to FIG. 8 and FIG. 9, the material 52 has a plurality ofpassageways 62 therethrough. Each passageway 62 has an inlet port and anoutlet port, identified by the number 64. Depending upon the orientationof the material 52, any port 64 may function as an inlet port or outletport. Each passageway 62 has an internal surface 66. Each passageway 62is generally cylindrical, passes from one side of material 52 to anopposite side, and it has a plurality of other passages 62 in fluidcommunication with and generally perpendicular thereto.

Referring again to FIG. 7, the usage and operation of the dehumidifier50 will be described in greater detail. The dehumidifier 50 may beplaced in any environment having water vapor or other compound orconstituent (for which dehumidifier 50 has an affinity) within a workinggas, such as air. When the heavier, denser compound/vapor laden gas(dotted arrows) enters an inlet port 64, it is dried by the surface areaof the adsorbent or hygroscopic material 52 within the correspondingpassageway 62. The lighter, drier air (clear arrows) thereafter exitsthrough a port 64. As the dry air rises, a circulation or “chimney”effect is created within the working environment, as illustrated by thearrows in FIG. 7. That is, the lighter, drier air rises from thedehumidifier 50 and the heavier, vapor laden air is circulated to enterthe dehumidifier 50 (through channels 58 or passages 62) so that thewater vapor or other constituent of the gas is adsorbed (or absorbed) bymaterial 52. Surfaces 54 and 56 may also provide some adsorption (orabsorption) of the gaseous constituent.

It is to be understood that the dehumidifiers 14, 30, and 50 may beconstructed of various shapes and sizes depending upon the working spaceto be dried. Further, the dehumidifiers 14 and 50 may be “tossed” intoan enclosed space, such as a case, and will always land and sit“upright” regardless of how they land. That is, the orientation of thedehumidifiers 14 and 50 is always consistent and appropriate regardlessof which “side” they rest upon. It is also to be understood that thematerial 16, 32 and 52 may be natural zeolite and that the dehumidifiersof the present invention may be useful in archival of museum,photographic, and other environmentally sensitive material, andprotective storage of industrial equipment, and any generally enclosedspace in which the humidity or concentration of a gaseous compound is ofconcern. The material 16, 32 and 52 may be shaped and the channels andpassages within the material 16, 32 and 52 may be formed by machining,extruding or pressing.

The present invention thus also provides a process for dehumidifying agas in an enclosed space, comprising the steps of forming a hygroscopicor adsorbent material into a shape which may be received within thespace and to circulate and dry the gas in a desired manner, such as bythe chimney effect described herein, activating or otherwise preparingor conditioning the material, such as by drying, and placing thematerial within the enclosed space. When the material has dried orotherwise adsorbed a sufficient or maximum amount of compound, it may beremoved from the enclosed space, reactivated through further drying, andreplaced within the enclosed space for additional drying of the space.Alternatively, the material may be reactivated or dried within theenclosed space without removal therefrom.

It is to be appreciated that the hygroscopic monolith of the presentinvention will seek equilibrium with the compound or constituent ladengas within the working space, such activity being facilitated by theshape and surface area of the monolith so as to passively interact withthe gaseous environment. As such, the hygroscopic monolith of thepresent invention may also be used to humidify or otherwise provide agaseous compound or constituent to a working space. The monolith ischarged or conditioned by saturating the monolith with the water orother compound or constituent and placing it within the space having adrier humidity or other ability or affinity to cause the water or othercompound/constituent to mix with the gas. In this environment, adowndraft, rather than a chimney effect, is created. As illustrated inFIG. 10, the dehumidifier 14 may be utilized as a humidifier 14A suchthat the drier air (clear arrows) enters the humidifier 14A (passages22) and water vapor or other compound or constituent is adsorbed by thegas and flows outward from the humidifier 14A (dotted arrows). Similarresults can be obtained by saturating the hygroscopic material of FIG. 4or FIG. 7.

It is to be understood that the present invention provides the abilityto facilitate the chimney effect or downdraft effect provided by thehygroscopic monolith so as to modify the composition of a gas in anenclosed space and in a desired manner. For example, whendehumidification is desired, a greater surface area but smaller mass ofthe hygroscopic material generally results in a quicker drying but lessdrying capacity. Likewise, a smaller surface area but a greater massgenerally provides slower drying but a greater drying capacity. Also,when used as a dehumidifier, the hygroscopic monolith of the presentinvention is preferably placed in the bottom of an enclosure and whenused as a humidifier, it is preferably placed in the top of anenclosure. It is also to be understood that the channels and passagewaysin the hygroscopic monolith provide a high surface to volume ratio andmay be positioned to facilitate air density differences in and aroundthe monolith in the manner described herein.

While the hygroscopic monolith of the present invention has beendescribed in connection with preferred embodiments, it is not intendedto limit the invention to the particular form set forth, but on thecontrary, it is intended to cover such alternatives, modifications, andequivalents as may be included within the spirit and scope of theinvention as defined by the appended claims.

I claim:
 1. A hygroscopic monolith, comprising a hygroscopic material,said material having a plurality of generally flat polygonal-shapedexterior surfaces, said material having a generally straight passagetherethrough positioned to facilitate gas density differences, saidmaterial being shaped to facilitate mixing of a gas containing acompound by a chimney effect, whereby a first portion of said gascontacts an internal surface of said passage, at least some of saidcompound is adsorbed by the material, and a second portion of said gas,containing less compound than the first portion, exits said passage. 2.A hygroscopic monolith, as recited in claim 1, wherein said passage isgenerally cylindrical.
 3. A hygroscopic monolith, as recited in claim 1,wherein said internal surface of said passage is generally smooth.
 4. Ahygroscopic monolith, as recited in claim 1, wherein said passagedefines a cavity within said material extending from a first side ofsaid material to a second side of said material.
 5. A dehumidifier,comprising an adsorbent material for water vapor, said material having aplurality of exterior surface, said material having a generally straightpassage therethrough positioned to facilitate gas density differences,said material being shaped to provide a surface area for adsorption ofwater vapor from an ambient gas and facilitating mixing of said gas by achimney effect, whereby a portion of said water vapor containing gascontacts said material within said passage, at least some of said watervapor is adsorbed, and a portion of said gas exits said passage.
 6. Adehumidifier, as recited in claim 5, wherein said passage is generallycylindrical.
 7. A dehumidifier, as recited in claim 5, wherein saidpassage is generally smooth.
 8. A dehumidifier, as recited in claim 5,wherein said passage defines a cavity within said material extendingfrom a first side of said material to a second side of said material. 9.A dehumidifier, comprising an adsorbent material for water vapor, saidmaterial having a plurality of exterior surfaces, said material having aplurality of generally straight passages therethrough positioned tofacilitate gas density differences, said material being shaped foradsorption of water vapor from an ambient gas and facilitating mixing ofsaid gas by a chimney effect, whereby a portion of said water vaporcontaining gas contacts said material within said passages, at leastsome of said water vapor is adsorbed, and a portion of said gas exitssaid passages.
 10. A dehumidifier, as recited in claim 9, wherein saidpassages are generally cylindrical.
 11. A dehumidifier, as recited inclaim 9, wherein said passages are generally smooth.
 12. A dehumidifier,as recited in claim 9, wherein said passages define cavities within saidmaterial extending from a first side of said material to a second sideof said material.
 13. A hygroscopic monolith, comprising a hygroscopicmaterial having a passage therethrough positioned to facilitate gasdensity differences, said passage defining a cavity within said materialextending from a first side of said material to a second side of saidmaterial, said material being shaped to facilitate mixing of a gascontaining a compound by a chimney effect, whereby a first portion ofsaid gas contacts an internal surface of said passage, at least some ofsaid compound is adsorbed by the material, and a second portion of saidgas, containing less compound than the first portion, exits saidpassage.
 14. A process for modifying gas in an enclosed space,comprising the steps of: forming a hygroscopic material into a shapewhich is received within said space, said material having a plurality ofgenerally flat polygonal-shaped exterior surfaces, said material havinga generally straight passage therethrough positioned to facilitate gasdensity differences, thereby providing a chimney effect or a downdrafteffect; preparing said material to adsorb or desorb a constituent withinsaid gas; and placing said material within said enclosed space.
 15. Aprocess for dehumidifying gas in an enclosed space, comprising the stepsof: forming an adsorbent material for water vapor into a shape which isreceived within said space, said material having a plurality of exteriorsurfaces, said material having a generally straight passage therethroughpositioned to facilitate gas density differences, thereby providing achimney effect, whereby said gas density differences facilitateadsorption of water vapor by an internal surface of said passage;activating said material; and placing said material within said enclosedspace.